1. Technical Field
This invention generally relates to frame assemblies for sorting machines, and more particularly to a transportable, and elevatable, frame assemblies for sorting machines such as trommel and shaker screen assemblies wherein the infeed conveyor is attached to one portion of the frame and the trommel or shaker screen assembly is attached to the other portion of the frame assembly and where the entire frame assembly is positionable to both a horizontal transport position and an elevated operating position.
2. Background
Trommels and shaker screens, as known in the prior art, are sorting or screening machines which are used to separate, by size, aggregate material such as crushed rock, coal or wood chips, and a wide variety of other materials, into different sized groupings. With a trommel, this is accomplished by passing the material to be separated through a rotating cylindrical screen of a particular screen size. With a shaker screen, this is usually accomplished by use of an eccentric drive or an unbalance rotating weight to produce screen shaking.
Simple trommels may have only one screen sieve size and accomplish a single separating operation wherein the aggregate material that is small enough to pass through the screen is collected on to a moving conveyor, usually called the belly conveyor, underneath the rotating screen, and conveyed away to one location, while the material that is too large to pass through the screen eventually works its way down to the discharge end of the screen and is deposited either on another discharge conveyor or simply dumped on the ground.
Two stage trommel screens have two separate sieve sizes for the rotating screen, with the smaller sieve size being located at the infeed end of the rotating screen, and a larger sieve sized screen located nearer the discharge end of the rotating screen. With two-stage trommel screen assemblies, fine materials are first collected at the infeed end of the rotating screen and conveyed off to one location. Larger material that will pass through the larger sieve size located at the discharge end of the rotating screen is collected by a second conveyor, and conveyed to a second location, and the material that will not pass through any of the screen is discharged at the end and either conveyed away or dropped on the ground.
Shaker screen assemblies are similar, in many respects, to trommel assemblies. They may have one, two or even several shaker screens of differing screen sieve sizes, arranged in a descending stacked order, with the largest sieve size screen placed on top of the stack, with progressively smaller sieve size screens stacked underneath, in sequential order, for the material to be separated to pass over. Conveyor assemblies and drive systems, similar to those used with trommel assemblies, are also provided.
In order for a trommel assembly to work, the infeed end of the rotating screen must be elevated so that material that is infed into the infeed end of the rotating trommel screen will, as it is agitated, work its way down parallel to the longitudinal axis of the screen to the discharge end. If the infeed end of the rotating screen was not elevated, the trommel screen would eventually fill with oversized material and cease to function. The same is true for shaker screens. If one end is not elevated, the material to be separated will not work its way down the screens, and the assembly will cease to function to separate material.
In some applications, trommel and shaker assemblies can be more or less permanently located on site. Examples would include processing areas at coal mines and rock quarries. In these applications there is typically provided an infeed conveyor which is used to elevate the material to the infeed end of the trommel or shaker screen and drop it in. These infeed conveyors can be permanently mounted, and the mined or quarried material is brought to the trommel or shaker assembly for sizing, separating and processing.
In other applications, the trommel or shaker assemblies must be portable. The reason for this is that there may not be enough material located at the site to be sized and separated at any given time to facilitate continuous operation. Since trommel and shaker assemblies are often times large and very expensive pieces of machinery, it is not, cost justifiable to leave, in situ, a trommel or shaker assembly which will only be operated one or two days a week or month. An example of this type of application is a logging operation where tree stumps and slash from the logging operation are collected and ground into wood chips using a rotating tub grinder, such as that described in U.S. Pat. No. 4,997,135. Once a particular area has been logged and the tree stumps and slash collected from the area, there will be no more material to be ground and removed, and any trommel or shaker assembly that has been used to separate the material into various sizes will have to be moved to the next logging location.
In some logging operations, the ground wood chip material to be separated by use of the trommel or shaker assembly is not generated at a rate sufficient to justify the full-time use of the trommel or shaker assembly, and as a result, the trommel or shaker assembly is periodically brought to the site, used for a few days, and then moved on to another site. In these situations, transportable trommels or shakers can be economically justifiable, since the separated material can easily be separated into fine material which is of high economic value and generally used as mulch for gardens and flower beds, and the intermediate size material can be used as a fuel for power generation, or further processed into wood pellets for use in home heating. And finally, the oversized material can be reprocessed through a rotating tub grinder, so that all of the tree stumps and slash from the logging operation can be fully utilized as value added products in one form or another.
The problem in the prior art is the time it takes to transport the trommel or shaker assembly and set them up for use. For example, in use with logging operations to generate separated, sized wood chip material, the trommel or shaker assembly is transported by a convoy of trucks. One truck transports the trommel or shaker, the second transports the infeed conveyor, and a third transports a front end loader or other piece of industrial machinery which is used to load the material to be separated onto the infeed conveyor, and also the separated, sized material into trucks for transport from the site. If the infeed conveyor is a separate piece of machinery, it must be attached in some form to the trommel or shaker assembly, and this process can take several hours, even for a skilled crew. Thus, in the prior art, an operator would need an extra truck to transport the infeed conveyor, and extra time to set up the entire assembly for operation.
A prior art alternative is to eliminate the infeed conveyor altogether, and instead just provide for a permanent, fixed loading chute at the input end of the trommel or shaker screens. The problem with this arrangement is that the infeed end of the trommel or shaker screen must be elevated in order for the trommel or shaker to work effectively. Thus, a prior art infeed chute is generally located twelve to sixteen feet in the air, thus requiring the use of a larger front end loader capable of elevating its dump bucket far into the air. Not only does this increase the machinery requirements by requiring a larger front end loader, but it also reduces the cycle time of the front end loader, since it has to lift the material higher into the air in order to dump it into the infeed end of the trommel or shaker screen.
Accordingly, what is needed is a transportable sorting machine such as a trommel screen assembly or a shaker screen assembly where the infeed conveyor is formed as an integral part of the sorting machine, and where the entire assembly is positionable to a horizontal transport position which is within transportable trailer length restrictions, and where two portions of the frame can be quickly elevated to reposition the trommel or shaker assemblies to an operating position while the receiving end of the in feed conveyor remains at a lowered elevation.